关于点对多点的微波无线环路技术

本文介绍的点对多点的微波无线电技术是适用于单蜂窝结构的用户环路系统的无线环路方案.点对多点微波无线环路技术将能够适应对无线环路不断提出的各种新的要求和业务.     

无线接入技术的应用

从电信部门的业务提供点（如交换机,CATV中心）到用户之间的网络称作用户接入网,而无线接入是完成用户接入网的一种重要的接入方式。无线接入技术也称无线接续技术,或称无线本地环路（WLL）,其主要功能是以无线技术为传输媒介向用户提供固定或移动终端的业务。无线本地环路为有线接入提供了一种应用形式灵活、系统经济可靠、实现方便、维护简单的通话方案。因此,无线接入技术受到各国电信业的高度重视。一、国内无线接入技术选用及频率使用应注意的问题1．设备选型上要因地制宜,适度超前无线接入采用的技术多种多样,应用形式五花…     

无线本地用户环路在中国的应用前景和发展策略

本重介绍了电信网中无线接入网——无线本地用户环路体系结构及其特点，并将它与有线环路进行了对比，分析了它的市场前景及应用场合。本还比较了国际上几种有代表性的无线本地用户环路技术，探讨了其未来发展方向。最后对如何发展中国无线本地用户环路系统进行了分析。     

无线本地环路系统

无线本地环路系统（ＷＬＬ）是近年来发展起来的新技术，它向用户提供具有市话有线用户环路同等功能的电话业务，是一种低成本的无线传输系统。本文将介绍无线本地环路技术 发展背景、特点，并介绍无线本地坏路系统概况，最后介绍Ｍｏｔｏｒｏｌａ公司的ＰＡＣＳ（Ｐｅｒｓｏｎａｌ Ａｃｃｅｓｓ Ｃｏｍｍｕｎｉｃａｔｉｏｎｓ Ｓｙｓｔｅｍ）系统及我国发展无线本地环路技术的策略。     

无线本地环路(WLL)的应用和发展

本文首先对无线本地环路作了简单的介绍,然后对无线本地环路的几种技术方案作了扼要的评述,最后对其技术应用和前景进行了阐述。     

数字无线本地环路

简要介绍了无线本地环路的基本概念，采用的数字技术，ＴＤＭＡ和ＣＤＭＡ无线本地环路系统的结构，并指出无线本地环路在减少成本，灵活入网，扩展网络等许多方面的优势，对几种无线本地环路的容量作了比较，对无线本地环路的前景作了展望。     

无线Internet接入技术

在当今社会 ,移动电话、无绳电话、集群电话等无线话音设备已被普通大众广泛认识和接受。随着信息时代的到来 ,人们在习惯了以网络为重要工具获取信息之后 ,已不满足于以无线的方式仅仅来传输话音。用无线接入技术接入本地公众信息网 ,向用户提供数据业务将是无线技术未来发展的方向。移动通信经营商和互联网服务提供商也可以通过提供数据业务增强其市场竞争力。１无线接入技术类型我们知道 ,无线接入Ｉｎｔｅｒｎｅｔ所采用的技术是在向用户提供传统电信业务的无线本地环路（ＷＬＬ）技术的基础上发展、建立起来的。传统无线本地环路系统所…     

全无线接入的无线用户环路系统

数字无线用户环路系统是近年来发展起来的一种运用数字移动通信技术、数字微波技术、数字无绳电话技术等无线传输技术，结合市话交换技术向用户提供具有市话有线用户环路同等电话业务功能的低成本，具有相当容量的高效无线传输系统。作为市话有线用户环路的延伸或同等作用，数字无线用户环路系统不仅能在有线电路埋沟架线十分困难的环境下为用户接入市话公共网提供有效的方法和手段，同时也是使市话交换机的用户实装数得以迅速提高、用户环路覆盖距离得以扩大的有效途径。其主要适用范围是不易铺设电话线的地方，如新建小区、岛屿、山区、农村及不发达地区，具有建设周期短、费用低、安装维护方便的特点。主要体现在如下几个方面：     

哈尔滨市无线接入系统的应用

对无线本地环路系统进行了概述,主要介绍了无线接入系统的组成与技术性能,及其在哈尔滨市的发展与应用。     

无线本地环路技术

所谓无线本地环路(WLL）,就是采用无线技术,接入本地公众网,向用户提供电信业务,通过建立无线本地环路系统,可使已建立电信网的运营商利用现有的交换机资源,快速开展和经济地提供电信业务,避免与有线线路安装和维护有关的瓶颈;对新业务运营商来说,无线本地环路系统可使之能因电信政策变化获得更多的机会,在市场竞争中有立足之地。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.